Starting a vibration-based PdM program doesn't have to be traumatic

Here's how to establish an effective vibration-based predictive maintenance program

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Establishing a vibration-based predictive maintenance (PdM) program at your plant doesn’t have to be a traumatic experience

The main concern is to establish a program that’s cost-effective. A program that costs more to operate than it saves in unscheduled downtime is not an effective tool. 

The purpose of a vibration PdM program is to limit the amount of unscheduled downtime and to detect and remedy problems before they cause extensive damage to machines or personnel.

Developing a machine list

The first step in initiating a PdM program is to develop a list of machines critical to the operation of your facility. Note that these machines are not necessarily the largest or most expensive machines.  

The most successful PdM programs start small and grow. This allows the system to begin working without overwhelming the maintenance staff with its findings. During the initial start up, the number of problems found in machines will likely be high, especially for the older ones.

The machine list should be a detailed list and include the name and type of machine, as well as related components, such as the gearbox, bearings, couplings, sheave sizes, belts and the base used (grout or springs).  This information will be helpful when constructing the database and analyzing vibration data.

Outsource or in-house?

Now that the comprehensive critical machine list has been fine-tuned, it’s time to make an important decision that is crucial to the start of an effective program. It’s whether to administer the program in-house or with an outside vibration consultant.

When doing the program in-house, there are many factors to consider. One is what level in the corporate structure will the program reside. This must be determined early on because it involves the management of the program as well as data collection and analysis. Another concern is acquisition cost equipment and selection of data collectors and condition monitoring software.  However, the most important decision relates to the personnel that will be trained to operate the equipment and manage the program. Several employees should be trained in the use of equipment to prevent the program from failing because of personnel changes.

What equipment to purchase

The equipment purchase decision should not be made on price alone. Take a good look at the equipment and available support in your area. It’s a good idea to talk with service providers and see what they use. Data collectors and software packages are similar and differ mainly in the bells and whistles.

The most common type of data collectors use the Fast Fouirer Transform method of processing data, which works well with a vibration PdM program.  The software package should be capable of trending, as well as be compatible  with your current computer system. Purchase a software system that’s been around awhile and has had the bugs worked out. It also might be best to use the same data collectors and software as one of the local service providers. This provides  a second source of assistance besides the sales rep who sold you the equipment.

Take full advantage of training offered by your vendor.  Also consider training from a local service provider or user groups. There also are professional associations that offer educational courses and proficiency tests.

Outside vibration consultants

If an outside consultant will administer the program, the local service providers should be considered. They should be invited to your facility to make a presentation of their services and asked to provide a quotation based on your machine list. Other services they provide to accompany the vibration program should also be considered in this process.  Most service companies tend to keep up-to-date with the latest equipment and software and have highly trained personnel in database setup, data acquisition and data analysis.  During their presentation ask to see an example report from other programs. 

 

Vibration spectrum trended over time. This shows before and after the bearing was changed.

 

When the consultant prepares a report for your facility, it should be concise, easy to understand and include recommendations as to how to repair any machines having faults.  If the report structure doesn’t meet your needs, then address this situation with your consultant. It should be possible for the report to be customized for your needs.

Database construction

The next crucial step is constructing the database. It should be setup to optimize the capabilities of data acquisition equipment and software.

Information collected on the machine list should be exported to the database. Take the time to fully incorporate bearing and gearbox information. Many software packages allow you to input bearing and motor information, including automatic fault detection setpoints.

If you have variable-speed or variable-load equipment, make sure your software accommodates this information. Machine rotational speed is the key to data analysis.

Database hierarchy

 

Trend data from an alarm band

The databases are constructed in a tree type fashion.  The database is divided into routes, which are, in turn, delivered to specific machines. The machines receive multiple monitor points, with each monitor divided into multiple analysis parameters. The number of parameters available depends on the software package, but it’s usually between six and 12.  Each analysis parameter has a frequency range based on specified fault requirements. They also are given an alarm and alert value.

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